Australians are putting in some of the longest working hours in the world with one in five putting in at least 45 hours a week.

New figures compiled by the Australian Bureau of Statistics show more than 2 per cent or a quarter million people work at least 70 hours a week. Another 400,000 are working between 60 or 69 hours a week or, over a five-day working week, at least 12 hours a day.

Miners are doing the longest weeks of anyone in the country with more than a quarter doing between 60 and 69 hours every week. Seventeen percent of miners put in more than 70 hours.

Finding a miner who works fewer than 40 hours a week is difficult. They account for just 11 per cent of of the total mining workforce.

After miners, agricultural workers and those in the fishing industry put in some of the biggest working days with more than a third on the job at least 60 hours a week.

International studies routinely show Australians working, on average, 35 hours a week which is in the bottom half of developed countries.

But the ABS figures show a larger proportion of Australians work at least 40 hours a week compared to those in part-time work and completing less than 30 hours a week.

More than 2.6 million people work between 40 and 44 hours – more than complete a week of 35 to 39 hours.

Retail, accommodation, education and health have the highest proportion of part-time workers of any industry.

Of the 1.2 million people in retail about 45 per cent put in fewer than 29 hours a week.

The bureau also noted there are now just 1.6 million Australians in a union. Unionists now account for 15 per cent of the total workforce and just 11 per cent in the private sector.

It was a drop from 17 per cent from the middle of 2013.

But the ACTU disputed the figures, claiming figures from its 46 affiliated members showed total union membership at 1.8 million.

“Every day unions are looking for ways to represent Australian workers and it has become very clear that as workplaces modernize so must unions,” ACTU secretary Dave Oliver said.